Thermostatically controlled heating device



May 17 1932- R. w. BROWN THERMOSTTICLLY CONTR/OLLED HEATING DEVICE FildNov. 25 1927 INVENToR. Fm Y WE R 1:: WN-

' ATTORNEYS.

Patented May 17, 1932 UNITED STATES ROY W. BROWN, OF AKRON, OHIO,.ASSIGNOR TO THE FIRESTONE TIRE AND RUBBER COMPANY, OF AKRON, OHIO, ACORPORATION OF OHIO THERMOSTATICALLY CONTROLLEI) HEATING DEVICEApplication filed November 25, 1927.

This invention relates to electrically heated devices controlled bymeans of a thermostat.

An object of the invention is to devise a thermostatically controlledheating device wherein the thermostat is interposed between the heatingcoil and the element to be heated. Another object is to devise a'thermostat comprising a bi-metallic element which is free to contractat temperatures below operating heat. A further object is to devisemeans for causing the Contact points of a thermostat to slide over oneanother as the Contact isbroken.

The foregoing and other objects are obtained by the device illustratedin the drawings and described below. It is to be understood that theinvention is not limited to the specific form thereof disclosed herein.

Of the accompanying drawings,

Figure l is a side elevation of a device embodying the principles of theinvention;

Figure 2 is a vertical sect-ion thereof; and

Figure 3 is a transverse section taken on the line 3 3 of Figure 2.

For purposes of illustration, the invention has been embodied in abranding die heater, but it equally is adapted for use in solderingirons, fiat irons, melting pots, or any other electrically heateddevice. The device illustrated comprises a shell 10 to which is attacheda socket member ll for holding the branding or embossing die l2 or otherelement to be heated. A sleeve 13, rotatable about member l1 is providedwith bayonet slot-s 14 for engaging bayonet lugs l5 on die l2 to securethe latter in the socket. The heating element is in the form of a coil16 wound about a tube 17 positioned Within shell l0, the heat beingtransmitted to the die through a rod 18 of copper or other good heatconductor projecting into the die and extending within tube 17. One endof the coil connected to the electric terminal i9 and the other end isconnected to one Contact point 2O of a thermostatically operated circuitbreaker. 'The second electric terminal 2l is connected to the othercontact point 22 t irough an arcuate leaf spring 23 fixed at one end topost 24, the tension of the spring serving to urge the contact pointstogether. An arcuate Serial No. 235,445.

loi-metallic strip 25 is also fixed at one end to post 2% and ispositioned within spring 23 and adjusted so that when the desiredtemperature of die l2 is obtained, strip 25 will expand sufiiciently toengage spring 23 and separate the points 20 and 22 as shown in thedotted lines in Figure 3 to break the circuit. As the contact is brokenthere is a` tendency for one point to slide over the other slightly,this wiping action serving to keep the contact surfaces clean. l/Vhenthe temperature falls below operating heat, strip 25 contracts andspring 23 forces the contact points together re-establishing thecircuit. Since the bi-nietailic strip is separate from the contactspring, the former is free to contract Without stress when use of thedevice is discontinued and the heat decreases to normal roomtemperature. Thus there is no tendency for the iii-metallic strip to bebent outwardly to lose its adjustment upon cooling. Greater uniformityof operating temperature is obtained by so constructing the thermostatand by interpcsing the same between the source ofheat and the element tobe heated as disclosed.

Modiications of the structure disclosed herein may be resorted towithout departing from the spirit of the invention or the scope thereofas defined by the appended claims.

What is claimed is:

l. A device of the class described comprising a pair of relativelymovable contact points, means for yieldingly urging said points intocontact to establish an electrical circuit, and means expandible by heatfor sliding one contact point over the other to clean the surfacesthereof, and for separating said points to break said circuit.

2. A device of the class described comprising a pair of relativelymovable contact points, an arcuate spring upon which one of said pointsis mounted and yieldably urged against said other contact point to closean electrical circuit, and an arcuate bi-metallic strip expandible byheat and engageable laterally of' said arcuate spring to cause onecontact point to slide over the other and to separate the points to openthe electrical circuit.

ROY W. BROVN.

